Rui Ueyama e3ea91c6f5 Optimize StringTableBuilder. ...

This is a patch to improve StringTableBuilder's performance. That class'
finalize function is very hot particularly in LLD because the function
does tail-merge strings in string tables or SHF_MERGE sections.

Generic std::sort-style sorter is not efficient for sorting strings.
The function implemented in this patch seems to be more efficient.

Here's a benchmark of LLD to link Clang with or without this patch.
The numbers are medians of 50 runs.

-O0
real 0m0.455s
real 0m0.430s (5.5% faster)

-O3
real 0m0.487s
real 0m0.452s (7.2% faster)

Since that is a benchmark of the whole linker, the speedup of
StringTableBuilder itself is much more than that.

http://reviews.llvm.org/D14053

llvm-svn: 251337

2015-10-26 19:58:29 +00:00

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MCDisassembler

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MCParser

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CMakeLists.txt

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ConstantPools.cpp

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ELFObjectWriter.cpp

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LLVMBuild.txt

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MachObjectWriter.cpp

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Makefile

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MCAsmBackend.cpp

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MCAsmInfo.cpp

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MCAsmInfoCOFF.cpp

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MCAsmInfoDarwin.cpp

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MCAsmInfoELF.cpp

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MCAsmStreamer.cpp

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MCAssembler.cpp

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MCCodeEmitter.cpp

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MCCodeGenInfo.cpp

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MCContext.cpp

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MCDwarf.cpp

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MCELFObjectTargetWriter.cpp

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MCELFStreamer.cpp

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MCExpr.cpp

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MCInst.cpp

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MCInstPrinter.cpp

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MCInstrAnalysis.cpp

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MCInstrDesc.cpp

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MCLabel.cpp

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MCLinkerOptimizationHint.cpp

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MCMachObjectTargetWriter.cpp

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MCMachOStreamer.cpp

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MCNullStreamer.cpp

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MCObjectFileInfo.cpp

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MCObjectStreamer.cpp

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MCObjectWriter.cpp

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MCRegisterInfo.cpp

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MCSchedule.cpp

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MCSection.cpp

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MCSectionCOFF.cpp

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MCSectionELF.cpp

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MCSectionMachO.cpp

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MCStreamer.cpp

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MCSubtargetInfo.cpp

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MCSymbol.cpp

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MCSymbolELF.cpp

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MCSymbolizer.cpp

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MCTargetOptions.cpp

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MCValue.cpp

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MCWin64EH.cpp

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MCWinEH.cpp

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StringTableBuilder.cpp

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SubtargetFeature.cpp

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WinCOFFObjectWriter.cpp

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WinCOFFStreamer.cpp

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YAML.cpp

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